1. Field of the Invention
This invention concerns a device for taking long-distance images. It applies, in particular, to video-surveillance and intelligence.
2. Description of the Related Art
The use of zoom, or variable focal length, lens units is known in the video-surveillance field, in order to have alternately wide or narrow optical fields. However, zooms have too short a focal length for many applications where it is necessary to have a very confined optical field, for example from several meters to a distance of several kilometers.